To me it doesn't make sense for FB to buy Kickstarter. FB wouldn't gain any particular advantage by buying Kickstarter. It isn't in the social space and there is little Kickstarter can do to disrupt FB (unlike mobile messaging apps like WhatsApp). Also FB can afford to buy successful projects that Kickstarter kickstarts like they did with Oculus.

Now if they buy a company like GitHub, that'd be a game changer but I hope that the GitHub founders hold on to it and never sell because from what I can tell GH are already profitable with a nimble team and already have investors like a19z if they need more funding. Besides the only reason to sell would be for founders wanting to become instant billionaires, and I hope that they recognize GH as something that they can work on their entire lives as inherently more valuable than a billion in the bank.

GH is the only social network that has the most developer mind share and is likely to be worth 1.5x or greater than WhatsApp from my perspective.